My Mercury 3. Despite occasional runs in my tank, it stopped working. That was a year ago. Now, I just repaired it.
Mecury 115 4 stroke motor issues
My little Mercury 3. Fuel leak from carby out the air inlet. Been two years now and I have done one trip up river in my dinghy with Parsun 9. For the first year, practically every month, I ran the motor at home in a tank. Fuel had preserver stuff added.
Then I missed three months and when I tried to start the little Mercury, fuel overflowed the carburettor and dripped out. After much pulling on the cord and turning the tap on and off and using no choke with full throttle, the motor started. It ran wonky. Perhaps fuel had gummed up the carby. It ran enough that I really wanted to go to the river above the barrage, fresh water, and give the motor a good run. Maybe that would clear it out. The next day I had opportunity. Once in the water — and feeling awesome because I practically never see the river — the motor took ages to start.
A small leak of fuel from the carburettor air intake portended problems. However, the motor did start and off I went. At home with motor in the tank, I managed to get it running. But on full throttle it was only chugging and would go no faster. Bit of fuel coming out of the air inlet. Needle valve stuck in carby? While I am no mechanic and a total newbie at outboard fixing, I tentatively persevered until I pulled the carburettor off. Helped by directions Everything looked totally clean.
Needle valve which controls fuel into the carby seemed fine. Put it all together.UPDATE Misdiagnosed How to troubleshoot 90hp Mercury outboard 4 stroke fuel issues Part 3
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Put the boat in shop with a mercury mechanic and he found nothing wrong based on computer and running it in a tank. Took out the day I picked it up and ran like a dream approximately 2 miles down the river fished for a while then ran back without any issues.
Same as first time jerking and stopping then jerking finally dieing. Ran trolling motor for approximately 30 mins and still wouldn't stay running. TUrned over battery acted fine just wouldn't stay running. Pumped bulb and it got hard but went soft while trying to start. I thought it might be a battery issue so I hooked motor up to trolling battery and idled for approximately 1 mile no problem. Couldn't get into throttle or motor would die.
Finally limped back to landing with trolling motor and motor cranked and put it on the trailer with motor. When I got home I cranked motor in driveway and ran for approximately 30 mins without a problem at idle speed. Removed hose after bulb and pumped tons of gas out when pumping bulb. So I am assuming nothing is blocking the line between motor and tank.
Can a battery be good enough to start the motor but not to give it power when you go to WOT? Over heating? I am lost. I didn't get any overheating alarms on the water. Help please! Bamaman1 Lieutenant Commander.Quick links. Mercury 4 stroke fuel problems You know the drill.
Boat in the shop for at least 7 weeks of the season so far and a new FSM float switch on order to be installed. Shop says the part is on it's 5th part revision - what does that tell you?
And switch failure does not set a code. This isnt caused by ethanol, but by cheap OEM sourcing by Merc. Next time, it'll be a Honda for me. Cheers, Chris on laDiabla. Last edited by BobG on Fri Sep 14, pm, edited 1 time in total. Except that the part has undergone minor revisions.
You would actually need to know the timeline of those 5 revisions they may have been years apart or they could have been running single batches of each part revision quick patch engineering can get you in trouble if proper QA steps with regression testing are not performed. Thanks for looking at to more impartially than me. I did find the key to the problem on this forum and on Boston Whaler forums. Here's a link to another fellow who had the exact same issue and resolution as me on this very forum.
A prior rant by me was misguided, but defensible in that the shop blamed bad gas cuz it was an easy cop out for them. Cheers, Chris. Whether your next engine is a Honda or not, you can still thank Yamaha and Honda for driving Mercury to build a better product. I have done this numerous times with all different products and services,,I do it in a constructive and respectful manor. It's amazing what you do get accomplished!!! Just remember the dealers are just a middle man.
I know my setup is new enough to handle ethanol, but I have managed to find more pure gas lately and have, and will continue to, only run pure gas from here on if I can get it. Blankety blank government! Ed, Cheryl, Ethan and Aspen. Chesapeake City ,MD. Where is that? Start with customer relations and see where that goes.This is the best Mercury Outboard Forum on the internet, it's yours!
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Put your boat info, outboard make and model or basic detail in the post title. Mercury outboard engine problems and issues? Then use this forum and maybe someone can help. Close Help. Entering your problem or issue is easy to do. Just type! No short 10 word descriptions, give as much detail as you can. If its written badly or doesn't make sense, sorry but it will not get posted. Your story will appear on a Web page exactly the way you enter it here.From reading the many threads here about this phenomenon, I've discovered there are three ways this breaks: --for some, they never have a problem at all; --for others, they let old fuel sit too long, get the carburetorss cleaned, and it works fine again until they let it sit too long--at least it's a predictable thing that happens to all carburetor outboard engines and yard tools; --the most unfortunate group develop problems early, and a thorough carburetor cleaning only works for a VERY short time, and it happens repeatedly.
It is the third group I am referencing, and from fishing needles out of the various thread haystackes here I have come up with what I think may be the cause for the problems plaguing group three.
115 Mercury 4 stroke problems
I believe these carburetors have a protective coating on their insides, that when compromised, allows phase-separated ethanol or the water drawn in by such to corrode the aluminum. At this point in the fuel system, all the filtering in the world is worthless, because the there are no more filters between the fuel and the tiny jets and orifices. So a cleaning gets rid of the debris--for a short time--and then it happens all over again.
The handful of marine technicians, that have a true understanding of this problem, end up replacing the pitted float bowls. In the worst case, the carburetor body itself needs replacing. Not very happy news overall for group three.
Just a theory as to why. Of the many threads here complaining of problems with these motors, not a single one that I have seen yet, has the original poster returned with a resolution: "fixed it by doing this I'd love to hear what has come of the problematic motors in this family, that readers have struggled with.
I will be relieved to have a Yamaha on the transom as many in the used market have. Some later model Makos have had some problems you may wish to learn about preparatory to your purchase. I believe there is a Mako owners site. A search on THT may also be helpful. He never did say what became of his particular carbureted Mercury FourStroke. Newt, was your carbureted FourStroke a 70, 90, or ?
What became of your motor? Or are you still using it? BTW, is there some inside joke about capitalization of model names?Back to the main site. Forums New posts Search forums. Media New media New comments Search media. Members Current visitors New profile posts Search profile posts Birthday calendar.
Thread starter dmctruby Start date Jul 31, Messages Reaction score 8. This year, last month it began hesitate when throttling up and would not exceed rpm. I would have to shut down and restart several times and reattempt full throttle before it would run normally.
It also randomly had starting issues and some idling problems. All inconsistent. Fine one hour and not working the next. I do have clean fuel filters hi and low pressure, new gas, water separator so I am pretty sure it is not an issue with the gas. These motors do have a tell tale sign there is an issue with the complex fsm fuel supply module If you check your air filter on the air intake and it is falling apart bits will get sucked into your engine.
That degrading of the foam is from excessive gas fumes in the vent eating the filter. So I did have that issue. The intakes were cleaned. The dealer is now looking at the rest of the engine. I am convinced oneseveral or all of the fsm elements are defective. There several elements in that system. One I know is some type of fuel float that hangs up. Other elements that manage the fuel I think could also be bad. The dealer is doing some other checks first but I am watching my prime boating weeks disappear here and was hoping some one else may have found and fixed the problem.
At the very least if you have a Merc 4 stroke go check your air filter and make sure it is not degrading and going into your engine. It will fall apart if really bad.
Early stage damage will just show the filter to be very tacky or gooey and ready to break down. No one is running with a Merc 4 stroke? Sorry I have a Yamaha Best of luck though! Messages 2, Reaction score 1,Which makes people wonder:. This will be all the information that you need to know about what problems Mercury Verado Engines have had, through the years.
These squirters would squirt oil on the back of the pistons to further lubricate the cylinders. Which is why they only came out with up to HP engines. That is because was the maximum HP that the block could produce.
No matter what PCM you put on it. One of the main problems of that block was, over time, the engine would jump timing. Being that the engine is an interference motor, once it jumps time, it can smash the valves to pieces and be nothing more than a really good anchor!
Just a fancy way of saying that when the pistons come up, the valves go down. If the timing is incorrect by more than 1 tooth, then the pistons can come up and smash the valves down, destroying the engine! The Verado runs on a timing chain, which makes for a great, maintenance-free valve train.
So if these early design blocks jump timing, it could be a serious issue.
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Unless it only jumps a single tooth. Then the timing chain could be put back on and get the engine back in time without any issues. One other problem that was common for these engines was that they would lose compression on the bottom two cylinders! These problems were common during the transitional phase of the Verado Evolution, from Around the Design II came out and all of these issues had been resolved.
Note that if you run an engine at wide-open throttle and go directly back into reverse, the motion of the boat and the propeller can cause the engine to jump timing. You can also blow up the lower unit. Even worse, a wave of water can come up over the engine and suck in water through the exhaust, blowing up the powerhead!
Pay close attention to your surroundings and your heading. Another problem that was going on during those first few flagship years of the Mercury Verado is that the bell crank would seize up and stick; leaving you unable to control the shifting of the engine! Fixing this issue required the unbolting of the engine mounts and pushing the engine up out of the cradle mount to change out the bell crank that attached to the shift shaft going down to the lower unit.
Mercury put out an immediate service bulletin and warranty claim for all of the serial numbers that were affected by this problem. Thankfully, because of their quick action and the lifetime warranty claim for the issue, the problem was mostly resolved.